UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Item 1.

Security and Issuer.

The class of equity securities to which this statement relates is the Common Units representing limited partnership interests (“NGL Common Units”) in NGL Energy Partners, L.P., a Delaware limited partnership (the “Issuer”). The principal executive office of the Issuer is located at 6120 South Yale Avenue, Suite 805, Tulsa, Oklahoma 74136.

Item 2.

Identity and Background.

(a)                                 This Schedule 13D is being jointly filed, pursuant to a Joint Filing Agreement attached hereto as Exhibit 1, by the following persons (collectively, the “Reporting Persons”):

(i)                                EMG NGL HC, LLC, a Delaware limited liability company (“EMG NGL HC”);

(ii)                             NGP Midstream & Resources, L.P., a Delaware limited partnership (“EMG Fund I”);

(iii)                          NGP MR, LP, a Delaware limited partnership (“EMG Fund I GP”);

(iv)                         NGP MR GP, LLC, a Delaware limited liability company (“Ultimate GP”);

(v)                            John T. Raymond; and

(vi)                         John G. Calvert.

The Reporting Persons have entered into a Joint Filing Agreement, dated the date hereof, which is filed with this schedule as Exhibit 1 and incorporated into this Item 2 by reference, pursuant to which the Reporting Persons have agreed to file this statement jointly in accordance with the provisions of Rule 13d-1(k)(1) under the Act. Information with respect to each Reporting Person is given solely by such Reporting Person, and no Reporting Person assumes responsibility for the accuracy or completeness of the information furnished by another Reporting Person. The Reporting Persons expressly disclaim that they have agreed to act as a group other than as described in this schedule. Pursuant to Rule 13d-4 of the Act, the Reporting Persons expressly declare that the filing of this statement shall not be construed as an admission that any such person is, for the purposes of Section 13(d) and/or Section 13(g) of the Act or otherwise, the beneficial owner of any securities covered by this schedule held by any other person and such beneficial ownership is expressly disclaimed.

Certain information required by this Item 2 concerning the officers and managers of the Reporting Persons is set forth on Schedule A, attached hereto, which is incorporated into this Item 2 by reference.

(b)                                 The principal business address of each of the Reporting Persons is:

(c)                                  The name and present principal occupation of each manager and officer of each of the Reporting Persons (collectively, the “Covered Individuals”) is set forth on Schedule A and is incorporated by reference in this Item 2.  The Covered Individuals together with the Reporting Persons are referred to as the “Covered Persons.”  All Covered Individuals are United States citizens. The principal business address of each of the Covered Individuals is set forth on Schedule A.

(d)                                 None of the Reporting Persons or, to the best of any Reporting Person’s knowledge, any of the Covered Individuals has, during the last five years been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

(e)                                  None of the Reporting Persons or, to the best of any Reporting Person’s knowledge, any of the Covered Individuals has, during the last five years been party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceedings was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

(f)                                   Each of EMG NGL HC, EMG Fund I, EMG Fund I GP and Ultimate GP are entities properly organized under the laws of the State of Delaware.  Each of John T. Raymond, John G. Calvert and the Covered Individuals are United States citizens.

Item 3.

Source and Amount of Funds or Other Consideration.

EMG NGL HC acquired NGL Common Units on June 19, 2012 in exchange for its common units representing limited partnership interests in High Sierra Energy, LP (“High Sierra”) pursuant to the High Sierra Merger Agreement and the transactions contemplated thereby (described in Item 4 below).

Item 4.

Purpose of Transaction.

(a)                                 See (b) below.

(b)                                 On June 19, 2012, the Issuer completed mergers with High Sierra and High Sierra Energy GP, LLC (“High Sierra GP”) pursuant to, respectively, (i) an Agreement and Plan of Merger, dated as of May 18, 2012 and attached hereto as Exhibit 2 (the “Merger Agreement”), by and among the Issuer, NGL Energy Holdings LLC, the general partner of the Issuer (“NGL GP”), HSELP LLC, a direct, wholly-owned subsidiary of the Issuer (“HSELP”), High Sierra and High Sierra GP and (ii) an Agreement and Plan of Merger, dated as of May 18, 2012 and attached hereto as Exhibit 3 (the “GP Merger Agreement”), by and among NGL GP, High Sierra GP and HSEGP LLC, a direct, wholly-owned subsidiary of NGL GP. The Merger Agreement and GP Merger Agreement provided for, respectively, (i) the acquisition of High Sierra by the Issuer, whereby HSELP merged with and into

High Sierra with High Sierra as the surviving entity and (ii) the acquisition of High Sierra GP by NGL GP, whereby HSEGP merged with and into High Sierra GP with High Sierra GP as the surviving entity (collectively, the “Merger”).

In connection with the Merger, the Issuer paid aggregate consideration of $693 million, including $153 million in cash, assumed indebtedness of $95 million and $445 million in equity. Pursuant to the Merger Agreement, each common unit representing limited partner interests in High Sierra (the “High Sierra Units”) was converted into the right to receive cash and NGL Common Units, based on a value of $21.50 per NGL Common Unit. As such, EMG NGL HC received 5,696,634 NGL Common Units in exchange for its High Sierra Units. Additionally, the Issuer’s membership interest in HSELP was converted into a 99% limited partner interest in High Sierra, as the surviving entity.

(c)                                  Not applicable.

(d)                                 Pursuant to Section 5.13 of the GP Merger Agreement, Patrick Wade was appointed by EMG NGL HC to the Board of Directors of NGL GP. NGL GP controls the Issuer through its directors. Other than the appointment of Mr. Wade in connection with the Merger, none of the Reporting Persons has any plan or proposal of the type referred to in clause (d) of Item 4 of Schedule 13D.

(e)                                  Not applicable.

(f)                                   Not applicable.

(g)                                  Not applicable.

(h)                                 Not applicable.

(i)                                     Not applicable.

(j)                                    Not applicable.

References to and descriptions of the Merger, the Merger Agreement and the GP Merger Agreement in this Item 4 are qualified in their entirety by reference to the Merger Agreement and the GP Merger Agreement, which are filed as Exhibit 2 and Exhibit 3, respectively, to this Schedule 13D and is incorporated into this Item 4 by reference.

The NGL Common Units described herein were acquired for investment purposes.

The Reporting Persons will continuously evaluate the Issuer’s businesses and prospects, alternative investment opportunities and all other factors deemed relevant in determining whether additional NGL Common Units will be acquired by any of the Reporting Persons or by other affiliated investment funds and accounts or whether any of the Reporting Persons or any such other affiliated investment funds and accounts will dispose of units. At any time, additional units may be acquired or some or all of the units beneficially owned by the Reporting Persons may be sold, in either case in the open market, in privately negotiated transactions or otherwise.

Other than as described in this Schedule 13D, none of the Reporting Persons or, to their best knowledge, any Covered Persons have any current plans or proposals that would be related to or would result in any of the matters described in Items 4(a)-(j) of Schedule 13D; however, as part of its ongoing evaluation of this investment and investment alternatives, the Reporting Persons may consider such matters in the future and, subject to applicable law, may formulate a plan with respect to such matters, and, from time to time, the Reporting Persons may hold discussions with or make formal proposals to management or the Board, other holders of units or other third parties regarding such matters.

Item 5.

Interest in Securities of the Issuer.

(a)         The information contained on the cover pages and in Items 2 and 4(b) of this Schedule 13D is incorporated herein by reference.

After giving effect to the Merger Agreement and the transactions contemplated thereby, EMG NGL HC became the beneficial owner of 5,696,634 NGL Common Units representing an approximate 11.59% interest in the Issuer. By nature of its controlling 65% membership interest in EMG NGL HC, EMG Fund I may be deemed a beneficial owner of the 5,696,634 NGL Common Units held by EMG NGL HC. As the general partner of EMG Fund I, EMG Fund I GP may be deemed a beneficial owner of the 5,696,634 NGL Common Units held by EMG NGL HC. As the general partner of EMG Fund I GP, Ultimate GP may be deemed a beneficial owner of the 5,696,634 NGL Common Units held by EMG NGL HC.

Pursuant to authority granted to them under the Limited Liability Company Agreement of Ultimate GP, dated February 16, 2007 (the “LLC Agreement”), John T. Raymond and John G. Calvert, as Chief Executive Officer and Managing Partner and as Chief Operating Officer and Managing Partner, respectively, of Ultimate GP, as the general partner of EMG Fund I GP, as the general partner of EMG Fund I, and by nature of EMG Fund I’s controlling 65% membership interest in EMG NGL HC, may be deemed beneficial owners of the 5,696,634 NGL Common Units held by EMG NGL HC. Additionally, the terms of the LLC Agreement require that the Chief Executive Officer of Ultimate GP only take action when such action is also approved by another officer of Ultimate GP.  John T Raymond and John G. Calvert are the only officers of Ultimate GP, and they may not be removed nor may additional officers be appointed without the unanimous consent of the members of Ultimate GP. As such, the approval of both John T. Raymond and John G. Calvert is required for action to be taken on behalf of Ultimate GP, including the voting or disposition of investment securities.

Beneficial ownership of the NGL Common Units is being reported hereunder solely because each Covered Person may be deemed to have beneficial ownership of such NGL Common Units as a result of the relationships described under Item 2, Item 3 and Item 4 and the matters described in Item 3, Item 4 and Item 5 of this Schedule 13D.  Neither the filing of this Schedule 13D nor any of its contents shall be deemed to constitute an admission by any of the Covered Persons that it is the beneficial owner of any NGL Common Units referred to herein for purposes of Section 13(d) of the Act, as amended, or for any other purpose, and such beneficial ownership is expressly disclaimed.

The aforementioned ownership percentages are based on 49,136,700 NGL Common Units issued and outstanding as of February 7, 2013 as reported on the Issuer’s Quarterly Report on Form 10-Q for the quarterly period ended December 31, 2012. Outstanding units do not include 5,919,346 subordinated units, of which the reporting person owns none.

Neither the filing of this Schedule 13D nor any of its contents shall be deemed to constitute an admission by any of the Reporting Persons (other than by EMG NGL HC, solely with respect to its direct holdings of the NGL Common Units) that it is the beneficial owner of any of the NGL Common Units referred to herein for the purposes of Section 13(d) of the Act or for any other purpose, and such beneficial ownership is expressly disclaimed by each Reporting Person (other than by EMG NGL HC, solely with respect to its direct holdings of the NGL Common Units) except to the extent of such Reporting Person’s pecuniary interest, if any, in the NGL Common Units.

To the knowledge of the Reporting Persons, none of the Covered Persons directly owns any NGL Common Units; provided, however, that because of each Covered Persons’ status as a manager, general partner, director, executive officer or member of a Reporting Person, a Covered Person may be deemed to be the beneficial owner of the NGL Common Units beneficially owned by such Reporting Person. Each of the Covered Persons disclaims beneficial ownership of the NGL Common Units reported herein and the filing of this Schedule 13D shall not be construed as an admission that any such Covered Person is the beneficial owner of any securities covered by this statement, except to the extent of such Covered Person’s pecuniary interest, if any, in the NGL Common Units.

(b)         The Reporting Persons may be deemed to have shared voting or dispositive power of the 5,696,634 Common Units held by EMG NGL HC due to the terms of the LLC Agreement requiring that the Chief Executive Officer of Ultimate GP only take action when such action is also approved by another officer of Ultimate GP.  John T Raymond and John G. Calvert, the Chief Executive Officer and Managing Partner and Chief Operating Officer and Managing Partner of Ultimate GP, respectively, are the only officers of Ultimate GP, and they may not be removed nor may additional officers be appointed without unanimous consent of the members of Ultimate GP. As such, the approval of both John T. Raymond and John G. Calvert is required for action to be taken on behalf of Ultimate GP, including the voting or disposition of investment securities.

(c)          Except as set forth in this Schedule 13D, none of the Reporting Persons has effected any transactions in NGL Common Units in the past 60 days.

(d)         Not applicable.

(e)          Not applicable.

Item 6.

Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer.

Other than as described in Items 2, 3, 4 and 5, to the knowledge of the Reporting Persons, there are no contracts, arrangements, understandings or relationships (legal or otherwise) between any of the Reporting Persons and any person with respect to any securities of the Issuer, including, without limitation, the transfer or voting of any of the securities, finder’s fees, joint ventures, loan or option arrangements, puts or calls, guarantees of profits, division of profits or loss, or the giving or withholding of proxies or any pledge or contingency, the occurrence of which would give another person voting or investment power over the securities of the Issuer.

Item 7.

Material to be Filed as Exhibits.

Exhibit 1                                               Joint Filing Agreement (filed herewith).

Exhibit 2                                               Agreement and Plan of Merger, dated May 18, 2012, by and among the Issuer, NGL GP, HSELP, High Sierra and High Sierra GP (incorporated by reference to Exhibit 2.1 to the current report on Form 8-K as filed with the Securities and Exchange Commission on May 21, 2012).

Exhibit 3                                               Agreement and Plan of Merger, dated May 18, 2012, by and among NGL GP, High Sierra GP and HSEGP (incorporated by reference to Exhibit 2.2 to the current report on Form 8-K as filed with the Securities and Exchange Commission on May 21, 2012).

Dated: May 15, 2013.

NGP MR GP, LLC

By:

/s/ John T. Raymond

John T. Raymond

Chief Executive Officer and Managing Partner

By:

/s/ John G. Calvert

John G. Calvert

Chief Operating Officer and Managing Partner

NGP MR, LP

By:

NGP MR GP, LLC, its General Partner

By:

/s/ John T. Raymond

John T. Raymond

Chief Executive Officer and Managing Partner

By:

/s/ John G. Calvert

John G. Calvert

Chief Operating Officer and Managing Partner

NGP Midstream & Resources, L.P.

By:

NGP MR, LP, its General Partner

By:

NGP MR GP, LLC, its General Partner

By:

/s/ John T. Raymond

John T. Raymond

Chief Executive Officer and Managing Partner

By:

/s/ John G. Calvert

John G. Calvert

Chief Operating Officer and Managing Partner

EMG NGL HC, LLC

By:

NGP Midstream & Resources, its Member

By:

NGP MR, LP, its General Partner

By:

NGP MR GP, LLC, its General Partner

By:

/s/ John T. Raymond

John T. Raymond

Chief Executive Officer and Managing Partner

By:

/s/ John G. Calvert

John G. Calvert

Chief Operating Officer and Managing Partner

/s/ John T. Raymond

John T. Raymond

/s/ John G. Calvert

John G. Calvert

Name

Occupation

NGP Midstream & Resources, L.P.

65% Member

John T. Raymond

Chief Executive Officer and Managing Partner

John G. Calvert

Chief Operating Officer and Managing Partner

Name

Occupation

NGP MR, LP.

General Partner

Name

Occupation

NGP MR GP, LLC

General Partner

Name

Occupation

John T. Raymond

Chief Executive Officer and Managing Partner

John G. Calvert

Chief Operating Officer and Managing Partner

Dated: May 15, 2013

NGP MR GP, LLC

By:

/s/ John T. Raymond

John T. Raymond

Chief Executive Officer and Managing Partner

By:

/s/ John G. Calvert

John G. Calvert

Chief Operating Officer and Managing Partner

NGP MR, LP

By:

NGP MR GP, LLC, its General Partner

By:

/s/ John T. Raymond

John T. Raymond

Chief Executive Officer and Managing Partner

By:

/s/ John G. Calvert

John G. Calvert

Chief Operating Officer and Managing Partner

NGP Midstream & Resources, L.P.

By:

NGP MR, LP, its General Partner

By:

NGP MR GP, LLC, its General Partner

By:

/s/ John T. Raymond

John T. Raymond

Chief Executive Officer and Managing Partner

By:

/s/ John G. Calvert

John G. Calvert

Chief Operating Officer and Managing Partner

EMG NGL HC, LLC

By:

NGP Midstream & Resources, its Member

By:

NGP MR, LP, its General Partner

By:

NGP MR GP, LLC, its General Partner

By:

/s/ John T. Raymond

John T. Raymond

Chief Executive Officer and Managing Partner

By:

/s/ John G. Calvert

John G. Calvert

Chief Operating Officer and Managing Partner

/s/ John T. Raymond

John T. Raymond

/s/ John G. Calvert

John G. Calvert